Ringer



June 1, 1937.

H. A BREDEHOFT 2,082,095

RINGER Filed July 27, 1935 2 Sheets-Sheet l llmlluf VIIIIIIIIIIII'.

/Nl/EN TOR By HABREDEHOFT A TTOPNE V June 1, 1937. I A BREDEHOFT2,082,095

RINGER Filed July 27, 1935 2 Sheets-Sheet 2 /N VE N TOR B y H. ,4.BREDEHOFT A 7' TORNEV Patented June 1 1937 UNITED STATES PATENT OFFICERINGER Application July 27, 1935, Serial No. 33,546

3 Claims.

This invention relates to electromagnetically operated ringing devicesand more particularly to devices of this kind commonly known astelephone ringers.

The object of this invention is to provide a telephone ringer whichafter proper adjustment to its chief operating characteristic will notchange its characteristic in service.

Features of this invention reside in a spring 1 support for thearmature, supporting means for the armature assembly, a biasing springarrangement for biasing .the armature, and means for removablysupporting a bell striker on the free end of a rod.

- In the drawings:

Fig. 1 is a top plan view of the ringer;

Fig. 2 is a side View, partly in section, taken on the line 22 in Fig. land viewed in the direction indicated by the arrows;

Fig. 3 is a view in perspective of parts of the ringer partly assembledand with a portion of one of the coils broken away; and

,Fig. 4 is a view in perspective of the electromagnetic driving coilassembly with parts of the coils broken away to disclose interiorportions of the structure and the armature and armature supportarrangement.

In electromagnetically operated bells it has been found that if anarmature is supported by pivot point screws, the friction at the pivotpoints changes in service and under various climatic conditions. Thesechanges necessitate rather frequent readjustments of the ringer to bringit back to its original operating characteristic. It has also been foundthat a certain spacing of an armature relative to end portions of thecores of the electromagnetic drive is important and that if any changeis made in the spacing of these parts the efiiciency of the ringer ischanged.

In the telephone service, ringers having various' operatingcharacteristics are required to meet various line conditions. Springsand adjustable cords attached to armatures have been provided 45 to biasthe armature relative to ends of the electromagnetic cores to meetcertain requirements. The springs and cords have a tendency to stretchin service and frequent readjustments of these parts are required.

50 Soft tone ringers are required in some cases while loud tone ringersarerequired in others.

This invention provides a ringer that meets the various requirementscalled for in the telephone service and which will not require frequentreadjustment.

In the drawings in which like numerals in the dilferent figures identifythe same parts, I is a U-shaped permanent magnet and 2 is a crossbar ofmagnetic material joining the two spaced ends of the permanent magnet I.The cross-bar 5 2 is secured to the ends of the permanent magnet ipreferably by welding the parts together and serves as a support for thespaced cores 3 and 4 of the electromagnets. The cross-bar 2 has a bellsupporting portion 5 extending upward from one side edge and normal tothe plane of the cross-bar 2. The bell supporting portion 5 has twodiverging arms 6 and 'l to which bells 8 and 9 are respectively attachedby suitable means such, for instance, as the screws H]. The bells 8 and9 are preferably supported on the respective arms 6 and l in an invertedposition as shown in Figs. 1, 2, and 3. The cores 3 and 4 are reduced indiameter at their respective upper ends II and 12 as shown in Figs. 3and 4 to pass through spaced apertures in a plate I3 whichserves as aspoolhead and is common to the two windings of the electromagneticdrive. The reduced ends I l and I 2 of the respective cores 3 and 4 areeach drilled and tapped to receive a machine screw I4. The machinescrews l4 extend through spaced apertures in the cross-bar 2 and threadinto the drilled and tapped reduced end portions H and I2 of the cores 3and 4 and secure the upper ends of the cores 3 and 4 to the cross-bar 2.

The plate I3 is a comparatively stiff rectangular strip of insulatingmaterial such, for instance, as phenol fibre and is provided with spacedapertures adapted to receive the reduced ends I l and I2 of the cores 3and 4. Adjacent the rear edge of the plate l3 are spaced apertures toreceive metal eyelets l5. The eyelets l5 serve to secure to the plate !3a metal strip [6 which forms an electrical connection between the twowindings of the electromagnets, ends of the windings being electricallyconnected to the eyelets l 5. Adjacent the front edge of the plate l3are two pairs of spaced apertures I! to accommodate tab terminals IS,the terminals l8 being secured to the plate !3 by metal eyelets 19. Themetal eyelets l9 extend through the tab terminals and through one ofeach pair of the spaced apertures l1 and clamp the tab terminals [8 tothe plate l3. A downwardly bent end portion of each tab terminal l8extends into the remaining aperture of each pair I! and preventsrotation of the tab terminal 18 on the plate 13. The tab terminals I8are electrically connected to free ends of the windings of theelectromagnets and serve as 55 points of connection between ends of thewindings and conductors of the telephone system. Spaced notches 2| areprovided along the front edge of the plate l3 for a purpose to besubsequently explained.

The windings 22 of the electromagnets are wound on the cores 3 and 4between the rectangular plate 13 and round spoolheads 23, the spoolheads23 being located on the lower ends of the cores 3 and 4.

The lower end of each core 3 and 4 has an enlarged portion 24 projectingbelow the spoolhead 23. The enlarged portion 24 is knurled with astraight knurl so that substantially sharp, vertical spaced ribs 25 areformed on the enlarged portion 24 of each core.

An armature 26 is provided to be operated by energizations of theelectromagnets. The armature 26 comprises a fiat portion 21 ofsuflicient length and width to cover the enlarged portions 24 of thecores 3 and 4 and to extend across the space between the cores 3 and 4.Spaced arms 26 extend upward from the sides of the fiat portion 21 inthe mid-section of the armature. The spaced arms 28 are downwardly sliton the upper ends at 29 to form spaced fingers 3|J-30. A leaf spring 3|is attached by rivets 32 to the upper face of the flat portion 21 of thearmature 26. The leaf spring 3| extends almost the full length of theflat portion 21 of the armature 26 and has free end portions that areturned slightly upward away from the upper surface of the fiat portion21. The free ends of the leaf spring 31 carry spaced embossings 33 and34. The embossings 33 extend upward from the upper face of the leafspring 3| and in line with the downwardly projecting cores 3 and 4. Theembossings 34 extend downward of the leaf spring 3| and toward the upperface of the fiat portion 21 of the armature 3|. The leaf spring 26 ismade of non-magnetic material such, for instance, as nickel-silver andserves as a buffer spring for the armature to prevent hammering of thearmature 26 against the ends of the cores 3 and 4 and also as anon-freeze element to prevent sticking of the armature to the cores dueto residual magnetism.

A yoke 35 and an armature supporting spring 36 are provided to supportthe armature 26 relative to the cores 3 and 4. The yoke 35 comprises twospaced ring portions 31 joined by a connecting bar 38. The ring portions31 are fiat rings having apertures 39 of a diameter slightly less thanthe outside diameter of the enlarged end portion 24 of the cores 3 and4. The ring portions 31 of the yoke 35 may be force fitted over theknurled ends of the enlarged portion 24 of the cores 3 and 4. Extendingupward from the connecting bar 38 are spaced arms 46, the upper ends ofwhich are downwardly slit at 4|, dividing the upper ends into two spacedfingers.

The armature supporting spring 36 comprises a flat strip of spring metalhaving a rectangular central portion 42 terminating at each end inreduced and longitudinally extending arms 43, the

:' outer ends of which terminate in enlarged end portions 44. The outeredges of the enlarged end portions 44 are notched at 45. Spaced notches46 are provided in the upper and lower edges of the central portion 42.Spaced apertures 41 are also provided in the central portion 42. Thelength of the rectangular central portion 42 of the spring 36corresponds to the distance between the upwardly extending arms 4|] ofthe yoke 35 plus the thickness of the two arms 46. The distance betweenthe spaced notches 46 on the upper edge of the rectangular portion 42 ofthe spring 36 and the distance between the notches 46 on the lower edgeof the spring 36 and the distance between the spaced apertures 41 in therectangular portion 42 of the spring 36 corresponds to the center tocenter measurement between the spaced arms of the yoke 35. The overalllength of the spring 36 corresponds to the distance between the arms 28of the armature 26 plus the thickness of the arms. The measurementbetween the notches in the upper edges of the enlarged end portions 44of the spring 36 and the distance between the notches 45 on the loweredges of the enlarged end portions 44 of the spring correspond to thecenter to center measurement between the arms 28 of the armature 26. Thedistance between the arms 28 of the armature 26 is greater than thedistance between the spaced arms 40 of the yoke 35 by an amount equal tothe combined length of the reduced portions 43 of the spring 36.

To mount the armature 26 relative to the lower enlarged ends 24 of thecores 3 and 4 the spring 36 is placed in the slits 4| in the upwardlyextending arms 40 of the yoke 35 so that the apertures 41 in the spring36 come between the spaced fingers of the arms 40 of the yoke 35. Thespaced fingers of the arms 40 are then squeezed together by means of asuitable pressure device to clamp the spring 36 between the spacedfingers of the arms 40 and to force some of the metal of the spacedfingers into the apertures 41 of the spring 36 and past the notches 46.This leaves the reduced portions 43 of the spring 36 extending outwardbeyond the spaced arms 40 of the yoke 35. The enlarged ends 44 of thespring 36 are then placed in the slits 29 of the spaced arms 28 of thearmature 26, with the arms 40 of the yoke 35 and the arms 28 of thearmature 26 both extending upward in parallel relation one with theother. The spaced fingers 30 of the arms 28 of the armature 26 are thensqueezed together by means of a suitable pressure device to clamp theenlarged ends 44 of the spring 36 between them and to force some of themetal in the spaced fingers 30 into the notches 45 in the outer ends ofthe spring 36. With the spring 36 clamped in the spaced arms 40 of theyoke 35 and the outer ends of the spring 36 clamped between the spacedfingers 3|) of the arms 28 of the armature 26 the armature 26 ispivotally supported by means of the spring 36 on the yoke 35 and beneaththe yoke 35.

After the armature 26 has been assembled on the yoke 35 the spaced ringportions 31 of the yoke 35 are force fitted onto the enlarged andknurled ends 24 of the cores 3 and 4 so that the ribs 25 of the knurledportions of the cores 3 and 4 slightly out into the metal surroundingthe apertures 39 in the rings 31 of the yoke 35. The adjustment of theyoke 35 on the knurled ends of the cores 3 and 4 is gauged so that thearmature 26 is spaced from the lower ends of the cores 3 and 4 apredetermined distance, the spacing of the parts having beenpredetermined by tests to find the spacing required for most efiicientoperation of the ringer. The adjustment of the yoke 35 on the knurledends of the cores 3 and 4 and the consequent spacing of the armature 26relative to the lower ends of the cores 3 and 4 is done at the factoryand since the ring portions 31 of the yoke 35 must be force fitted onthe knurled ends of the cores 3 and 4 the adjustment of the parts willnot change in service and cannot readily be altered by any one tamperingwith the apparatus. The

ringer therefore will not change its characteristic in service becausethe armature cannot be as a whole moved from its normal and requiredspacing relative to the cores of the electro magnets.

When the coils of the electromagnets are energized the armature 26 isrocked back and forth on its points of suspension which are the reducedportions 43 of the spring 36. The reduced portions 43 of the spring 36due to the character of the material from which the spring is formedhave a. tendency to resist the movements of the armature 26 and torestore the armature 26 to normal position.

Since the armature 26 in normal operation is never rocked to such anextent as to cause permanent distortion of the metal in the reducedportions 43 of the spring 36, the restoring characteristic of the spring36 will not be changed.

In the armature suspending means there are no pin pivot points in whichfrictional changes would occur with a change in temperature or climateor wearing of the parts. The ringer, therefore, will not change incharacteristic in service.

One of the spaced fingers 30 of an arm 28 oi the armature 26 is drilledand tapped to receive a threaded end of a striker rod 48. The strikerrod 48 carries on its upper end a striker holder 49 comprising a collarportion 56 and a reduced upper end 5|. The upper end 5| islongitudinally split to provide spring fingers 52. The spring fingers 52are deformed on the upper ends to provide a split knob 53. The splitknob 53 is adapted to receive a striker 54 which may be a tubular pieceof metal or other hard material if a loud ringing device is required ormay be a tube of wood or other comparatively soft material if a softringing device is required. The striker 54 may readily be removed fromthe striker holder 49 and replaced by another like element of differentmaterial as required.

One of the spaced fingers 36 of an arm 28 of the armature 26 islongitudinally drilled to receive a lower end of a biasing spring 55.The biasing spring 55 has a helical central portion 56 and comparativelystraight upper and lower portions 51 and 58 respectively. The lowerportion 58 is secured in the upper end of one of the spaced fingers 30of an arm 28 of the armature 26. The upper end of the spring 55 rests inone of the spaced notches 2| in the rectangular plate l3. Since thearmature 26 is supported on the yoke 35 by means of the spring 36,movement of the upper end 51 of the spring 55 from one notch 2| toanother notch 2| in the plate I3 will cause biasing of the armature 26relative to the pole pieces 3 and 4.

When the ringer is installed in a telephone substation the installer mayreadily change the bias of the armature relative to the cores of theelectromagnets to meet a line condition by moving the upper end of thebiasing spring 55 from one notch 2| to another notch 2| in the plate l3.ringer from a loud tone ringer to a soft tone ringer or vice versa asrequired by removing the striker 54 and replacing it with anotherstriker of different material. The spacing of the armature 26 relativeto the cores 3 and 4 of the electromagnets, however, cannot readily bechanged either intentionally or accidentally by the installer.

Although in the above description the spaced notches 2| for receivingthe free end of the biasing spring 55 have been described as beinglocated in an edge of the plate I3, the notches 2| might be located inan edge of the cross-bar 2 without departing from the spirit of theinvention.

What is claimed is:

1. In a telephone ringer, in combination, a pair of magnet cores, a yokeattached to the magnet cores, spaced arms on the yoke, a fiat springsecured in the spaced arms of the yoke, end portions of said springextending outwardly beyond said arms, an armature and spaced lugs on thearmature attached to said outwardly extending ends of said fiat spring.

2. In a telephone ringer, in combination, a pair of magnet cores, a yokesupported on said magnet cores, spaced arms on the middle portion ofsaid yoke, a flat spring secured in said spaced arms, free end portionsof said spring extending outwardly of said spaced arms, an armature andspaced arms on the middle portion of said armature and extendingupwardly about said yoke, and secured to the outwardly extending freeend portions of said fiat spring.

3. In a telephone ringer, in combination, a pair of magnet cores, a yokesupported on said magnet cores, spaced arms extending upwardly from themiddle portion of said yoke, a fiat spring secured edgewise in saidspaced arms, free end portions of said flat spring extending outwardlyof said spaced arms, an armature and spaced arms on the middle portionof said armature and extending upwardly about said yoke in parallelismwith the spaced arms of said yoke and secured to the outwardly extendingfree end portions of said flat spring, the efiective part of said flatspring being a relatively small portion of the length of said spring.

HAROLD A. BREDEHOFT.

The installer may also readily change the

